The present invention relates to an image processing apparatus, an image processing method, and a printer driver for converting multilevel pixel values (hereinafter abbreviated “pixel values”) in a display color space, associated with display colors of multicolor original image data, into pixel values in an ink color space (or print color space), associated with ink colors to be used for multicolor-printing a multicolor original with a plurality of color inks.
In general, in multicolor-printing a multicolor original with a plurality of color inks, it has been a usual practice to conduct “color separation” methods converting pixel values in a display color space (such as the RGB color space), associated with display colors of multicolor original image data, into pixel values in an ink color space (such as the CMY color space), associated with ink colors to be used for the multicolor-printing.
Such color separation methods are classified broadly into the following categories:
(a) a method, disclosed in Japanese Patent Application Laid-open No. 2001-277473, converting pixel values in the RGB color space into pixel values in the CMY color space by a conversion formula as typified by a Nuegebauer formula; and
(b) a method, disclosed in Japanese Patent Application Laid-open No. 2001-186368, converting pixel values in the RGB color space into pixel values in the CMY color space by a color conversion look up table (hereinafter called “color conversion LUT”).
In particular, the method (b) has been commonly used because it easily shifts a color range for favorable color reproduction.